The Music Timeline shows genres of music waxing and waning, based on how many Google Play Music
users have an artist or album in their music library, and other data (such as album release dates).
Each stripe on the graph represents a genre; the thickness of the stripe tells you roughly the
popularity of music released in a given year in that genre. (For example, the "jazz" stripe is
thick in the 1950s since many users' libraries contain jazz albums released in the '50s.) Click on the
stripes to zoom into more specialized genres.

Where does the data come from?

The Music Timeline is based on album and artist statistics aggregated from
Google Play Music — we define popularity
by how many users have an artist or album in their music library.

What do the colors mean?

Colors are used to visually separate genres and group sub-genres, but have no other meaning.

Is this data normalized?

Yes. There's lots of data about recent music, but the information about older music is more sparse;
shown directly, even major changes in the '60s are dwarfed by tiny twitches in the '90s.
Additionally, there's simply more music published now!
To keep the visualization legible, the overview data is normalized by the total number of
albums from that year — this way, you can see and understand the timeline across all the decades.

Why does the timeline start in 1950?

The data from earlier than 1950 is too sparse to visualize in this way.

Where is the classical music?

People usually think of classical music in
terms of its composition date, not its recording date — should a particular
concerto recording be dated when Mozart wrote it in 1791, or when the Boston Symphony
Orchestra performed it in 2009? Because of this difference, placing classical music on the
timeline the same way as contemporary music looks counterintuitive, so it is omitted from this
visualization.

Some albums are missing cover art!

Yes, we don't have album art to show for all artists and albums. Sorry!

Why do some albums appear more than once?

Many albums are released in slightly different versions for different countries. They might have
translated titles, new art, bonus tracks, or even a different track list altogether! This makes
it tricky to say precisely
what defines a release,
so some of these similar albums may appear separately.